title: An explanatory model of factors related to well baby visits by age three years for Medicaid-enrolled infants: a retrospective cohort study.
abstract: BACKGROUND
  Well baby visits (WBVs) are a cornerstone of early childhood health, but few studies have examined the correlates of WBVs for socioeconomically vulnerable infants. The study objective was to identify factors related to the number of WBVs received by Medicaid-enrolled infants in the first three years of life and to present a preliminary explanatory model.
  
  
  METHODS
  We analyzed Iowa Medicaid claims files and birth certificate data for infants born in calendar year 2000 (N = 6,085). The outcome measure was the number of well baby visits (WBVs) received by Medicaid-enrolled infants between age 1 and 41 months (range: 0 to 10). An ecological health model and existing literature were used to evaluate 12 observed factors as potential WBV correlates. We ran multiple variable linear regression models with robust standard errors (α = 0.05).
  
  
  RESULTS
  There were a number of infant, maternal, and health system factors associated with the number of WBVs received by Medicaid-enrolled infants. Infants whose mothers had a greater number of prenatal healthcare visits (ß = 0.24 to 0.28; P = .001) or were married (ß = 0.20; P = .002) received more WBVs. Having a chronic health condition (ß = 0.51; P < .0001) and enrollment in a case management program (ß = 0.48; P < .0001) were also positively associated with WBVs. Eligibility for Medicaid through the Supplemental Security Income Program (ß = -0.70; P = .001), increased maternal age (ß = -0.27 to -0.35; P = .004), higher levels of maternal education (ß = -0.18; P = .005), maternal smoking (ß = -0.13; P = .018), and enrollment in a health maintenance organization plan (ß = -1.15; P < .0001) were negatively associated with WBVs. There was a significant interaction between enrollment in a health maintenance organization plan and enrollment in a Medicaid case management program (P = .015). Maternal race, maternal alcohol use during pregnancy, and rurality were not significantly related to the number of WBVs.
  
  
  CONCLUSIONS
  Multiple infant, maternal, and health system variables were related to the number of WBVs received by Medicaid-enrolled infants. Additional research is needed to develop strategies to optimize access to WBVs for Medicaid-enrolled infants at risk for poor use of preventive medical care services.
authors.affiliation: Department of Oral Health Sciences, University of Washington, Box 357475, Seattle, WA 98195, USA. dchi@uw.edu.
authors.forename: Donald L
authors.initials: DL
authors.lastname: Chi
authors.forename: Elizabeth T
authors.initials: ET
authors.lastname: Momany
authors.forename: Michael P
authors.initials: MP
authors.lastname: Jones
authors.forename: Raymond A
authors.initials: RA
authors.lastname: Kuthy
authors.forename: Natoshia M
authors.initials: NM
authors.lastname: Askelson
authors.forename: George L
authors.initials: GL
authors.lastname: Wehby
authors.forename: Peter C
authors.initials: PC
authors.lastname: Damiano
mesh_terms: D000704:Analysis of Variance; D001719:Birth Certificates; D002662:Child Health Services / Q000706:statistics & numerical data*; D002675:Child, Preschool; D005260:Female; D006279:Health Maintenance Organizations / Q000706:statistics & numerical data*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007484:Iowa; D016014:Linear Models; D008297:Male; D008484:Medicaid / Q000706:statistics & numerical data*; D011314:Preventive Health Services / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D012943:Social Security / Q000706:statistics & numerical data*; D014481:United States